An air bag device for an occupant in a passenger seat or a rear seat protects the occupant by deploying an air bag when a vehicle comes into collision. The air bag device has the folded air bag, a retainer or a container for accommodating the air bag, a lid for covering the air bag, and an inflator (gas generator) for deploying the air bag. The air bag device is installed to an instrument panel, a back of a front seat, or the like of the vehicle.
In a conventional air bag device for a vehicle, various measures of improving the output of the inflator and of reducing the volume of the air bag have been taken in order to deploy an air bag rapidly in its fully deployed state to accomplish secure protection of an occupant.